Piston cooling jets or oil injectors may be implemented in an engine to provide engine cylinder cooling and lubrication. In particular, each oil injector sprays oil onto an underside of a corresponding piston to create a cooling effect on the piston. Furthermore, the oil propagates from the underside of the piston to the surrounding walls of a corresponding engine cylinder as the piston reciprocates in the engine cylinder to provide a cooling effect to the combustion chamber.
In one example, oil injector operation may be disabled at engine startup until the engine cylinders have reached an operating temperature that is suitable for stable combustion, at which point oil injector operation may be enabled. In this example, oil injector operation may be delayed to promote engine heating in order to reduce particulate matter generated as a result of incomplete combustion.
However, the inventors have recognized several potential issues with such an approach. For example, since the oil injectors are not operated until the engine reaches the designated operating temperature, there is a lack of initial lubrication of the pistons that causes piston slap and increased piston wear.
In one example, the above mentioned issues may be addressed by enabling oil injection onto a piston of an engine during an engine cold start event, disabling oil injection after the engine cold start event, and enabling oil injection after the engine cold start event based on a first operating parameter.
In one example, the oil injectors may be initially operated for just an initial few (e.g., 5-10) engine revolutions during the engine cold start event to suitably lubricate the pistons and cylinder walls. After the engine cold start event, the oil injectors may be disabled, and not operated for one or more engine cycles, to promote quick heating of the cylinders. In one example, the first operating parameter may be a designated operating temperature associated with stable combustion. Accordingly, operation of the oil injectors may be re-enabled after the cylinders have been heated to the designated operating temperature.
By initially enabling oil injection during the engine cold start event, noise, vibration, harshness (NVH) characteristics of the engine and wear on the pistons may be reduced relative to an approach that delays oil injector operation. In this way, drivability of the engine and an engine component lifespan may be increased.
Moreover, by disabling oil injection after the engine cold start event until the engine has reached a temperature suitable for stable combustion, and then re-enabling oil injector operation, the engine may be heated to an operating temperature more quickly than an approach that operates oil injectors continually from engine startup. In this way, particulate matter generated as a result of incomplete combustion may be reduced.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description, which follows. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined by the claims that follow the detailed description. Further, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.